1. Field of the Disclosure
This specification relates to a method of fabricating a flexible display device, and particularly, to a method of fabricating a flexible display device, capable of easily detaching an auxiliary substrate from a process-completed flexible substrate.
2. Background of the Disclosure
In recent information-oriented societies, importance of display devices as visual information transfer media is urged. To dominate an important position later, such display devices have to meet several conditions, such as low power consumption, size reduction, weight reduction and enhancement of image quality.
The display devices may be classified into light-emitting type display devices including a cathode ray tube (CRT), an electroluminescence (EL), a light emitting diode (LED), a vacuum fluorescent display (VFD), an organic light emitting device (OLED), a field emission display (FED), a plasma display panel (PDP), an electrophoresis display device, and light non-emitting type display devices such as a liquid crystal display (LCD).
A flexible display device which is not damaged even if it is folded or rolled up is expected to be highlighted as a new technology in the display device field. Many obstacles are existing in implementing the flexible display device at present, but a thin film transistor (TFT) LCD device, an OLED device or an electrophoresis display device will be the mainstream display device, with development of technologies.
A flexible display device is called as a scroll display device. The flexible display device is implemented on a thin substrate such as plastic. The flexible display device is not damaged even if being folded or rolled up like a paper, and thus it is considered as one of next generation display devices. LCD devices and OLED devices which can be made thin less than 1 mm are promising display devices at present.
The LCD device is a device for outputting an image using optical anisotropy of liquid crystal molecules. The LCD device exhibits higher visibility than the conventional CRT, and less average power consumption and less heat radiation than the CRT with the same screen size. Accordingly, the LCD device is under the limelight as the next generation display device.
The OLED device can emit light by itself, and accordingly exhibits high visibility even when it is used in a dark place or external light is shone and has the fastest response rate, which is an important reference for determining a performance of a mobile display device, among all existing display devices. Accordingly, the OLED device can implement perfect videos. Also, the OLED device can be designed into a ultrathin shape, which may allow various types of mobile devices, such as mobile phones, to be slimmer.
To implement the flexible display device, flexibility of a substrate has to be ensured. To ensure the substrate flexibility, a flexible substrate made of plastic or stainless steel (SUS) is being used instead of the conventional glass substrate.
As such, the flexible substrate such as the plastic substrate has to be used to implement the flexible display device. To convey the flexible substrate and carry out a series of processes, those processes are generally executed after attaching the plastic substrate onto a glass substrate using an adhesive. Due to the complicated attachment (adhesion) process and a plurality of lamination processes, defective devices and lowering of productivity may be caused.
That is, to attach the plastic substrate onto the glass substrate, a complicated adhesion process, such as removal of a lower release paper of an adhesive, lamination of the adhesive, removal of an upper release paper of the adhesive, lamination of the plastic substrate, and the like have to be sequentially carried out. Also, it is highly likely to cause a process error (defect), such as generating bubbles and spots during the lamination process. Specifically, the complicated adhesion process results in lowering of productivity.
When the plastic substrate adhered onto the glass substrate is conveyed in the adhered state and then fabrication of a display panel is completed through several processes, a process of separating (detaching) the glass substrate from the plastic substrate as a display panel is carried out.
Here, to detach the plastic substrate from the adhesive attached on the glass substrate, several conditions have to be met depending on the detachment process. Also, since the adhesive is attached on an entire front surface of the glass substrate, the detachment is not easy.
In recent time, a display panel is formed by executing processes after interposing a sacrifice layer between the plastic substrate and the glass substrate and then the glass substrate is separated from the plastic substrate by applying a laser release. Upon the laser release, a vacuum is formed between the plastic substrate and the glass substrate, which makes it difficult to separate the glass substrate. In this case, an impact may be applied to the display panel including the plastic substrate, which may cause a damage of the flexible display device.